leetcode-844-Backspace-String-Compare

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描述

Given two strings S and T, return if they are equal when both are typed into empty text editors. # means a backspace character.

Example 1:

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Input: S = "ab#c", T = "ad#c"
Output: true
Explanation: Both S and T become "ac".

Example 2:

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Input: S = "ab##", T = "c#d#"
Output: true
Explanation: Both S and T become "".

Example 3:

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Input: S = "a##c", T = "#a#c"
Output: true
Explanation: Both S and T become "c".

Example 4:

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Input: S = "a#c", T = "b"
Output: false
Explanation: S becomes "c" while T becomes "b".

Note:

  1. 1 <= S.length <= 200
  2. 1 <= T.length <= 200
  3. S and T only contain lowercase letters and '#' characters.

Follow up:

  • Can you solve it in O(N) time and O(1) space?

分析

可以用先进后出的栈的思想来解决这个问题。

解决方案1(Java)

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class Solution {
    public boolean backspaceCompare(String S, String T) {
        return realStr(S).equals(realStr(T));
    }
    
    private String realStr(String s) {
        StringBuilder result = new StringBuilder();
        for (char c: s.toCharArray()) {
            if (c == '#') {
                if (result.length() > 0) {
                    result.setLength(result.length() - 1);
                }
            } else {
                result.append(c);
            }
        }
        return result.toString();
    }
}

题目来源